Information for Patients / Medical Professionals

Tamiflu ® ( oseltamivir phosphate )

Side Effect Reporting

You may report side effects to the FDA at (800) FDA-1088 or

You may also report side effects to Genentech at (888) 835-2555.


TAMIFLU is indicated for the treatment of acute, uncomplicated illness due to influenza in patients 2 weeks of age and older who have been symptomatic for no more than 2 days.

TAMIFLU is also indicated for the prophylaxis of influenza in patients 1 year and older.

Efficacy of TAMIFLU in patients who begin treatment after 48 hours of symptoms has not been established.

TAMIFLU is not a substitute for early and annual vaccination as recommended by the Centers for Disease Control’s Advisory Committee on Immunization Practices (ACIP).

There is no evidence for efficacy of TAMIFLU in any illness caused by agents other than influenza viruses Types A and B.

Influenza viruses change over time. Emergence of resistance mutations could decrease drug effectiveness. Other factors (for example, changes in viral virulence) might also diminish clinical benefits of antiviral drugs. Prescribers should consider available information on influenza drug susceptibility patterns and treatment effects when deciding whether to use TAMIFLU.

Important Safety Information

Severe Allergic Reactions

  • TAMIFLU is contraindicated in patients who have had severe allergic reactions (such as anaphylaxis or serious skin reactions such as toxic epidermal necrolysis, Stevens-Johnson syndrome, or erythema multiforme) to any component of TAMIFLU.
  • In postmarketing experience, cases of anaphylaxis and serious skin reactions, including toxic epidermal necrolysis, Stevens-Johnson syndrome and erythema multiforme, have been reported with TAMIFLU. TAMIFLU should be stopped and appropriate treatment instituted if an allergic-like reaction occurs or is suspected.

Neurologic Symptoms

  • Influenza can be associated with a variety of neurologic and behavioral symptoms, which can include events such as hallucinations, delirium and abnormal behavior, in some cases resulting in fatal outcomes. These events may occur in the setting of encephalitis or encephalopathy but can occur without obvious severe disease.
  • There have been postmarketing reports (mostly from Japan) of delirium and abnormal behavior leading to injury, and in some cases resulting in fatal outcomes, in patients with influenza who were receiving TAMIFLU. Because these events were reported voluntarily during clinical practice, estimates of frequency cannot be made but they appear to be uncommon based on TAMIFLU usage data. These events were reported primarily among pediatric patients and often had an abrupt onset and rapid resolution. The contribution of TAMIFLU to these events has not been established. Patients with influenza should be closely monitored for signs of abnormal behavior. If neuropsychiatric symptoms occur, the risks and benefits of continuing treatment should be evaluated for each patient.

Bacterial Infections

  • Serious bacterial infections may begin with influenza-like symptoms or may co-exist with or occur as complications during the course of influenza.  TAMIFLU has not been shown to prevent such complications.

Limitations of Populations Studied

  • Efficacy of TAMIFLU in the treatment of influenza in patients with chronic cardiac disease and/or respiratory disease has not been established. No difference in the incidence of complications was observed between the treatment and placebo groups in this population. No information is available regarding treatment of influenza in patients with any medical condition sufficiently severe or unstable to be considered at imminent risk of requiring hospitalization. 
  • Efficacy of TAMIFLU for treatment or prophylaxis of influenza has not been established in immunocompromised patients.
  • Safety and efficacy of TAMIFLU for treatment of influenza in pediatric patients less than 2 weeks of age has not been established. 
  • Safety and efficacy of TAMIFLU for prophylaxis of influenza have not been established for pediatric patients less than 1 year of age.

Concurrent Use with Live Attenuated Influenza Vaccine

  • The concurrent use of TAMIFLU with live attenuated influenza vaccine (LAIV) intranasal has not been evaluated. However, because of the potential for interference between these products, LAIV should not be administered within 2 weeks before or 48 hours after administration of TAMIFLU, unless medically indicated.

Most Common Adverse Reactions

  • The safety profile observed in infants 2 weeks to less than 1 year of age was consistent with the established safety profile of pediatric subjects aged 1 year and above, with vomiting, diarrhea and diaper rash being the most frequently reported adverse reactions.
  • Adverse events that occurred more frequently in patients treated with TAMIFLU than in patients taking placebo and occurred in  ≥2% of patients were (TAMIFLU %, placebo %):
    • Treatment in adults—nausea (10%, 6%), vomiting (9%, 3%), 
    • Treatment in pediatrics—vomiting (15%, 9%), abdominal pain (5%, 4%), ear disorder (2%, 1%)
    • Prophylaxis of adults—nausea (7%, 3%), diarrhea (3%, 2%), vomiting (2%, 1%), abdominal pain (2%, 1%)
    • Prophylaxis of pediatrics—vomiting (10%, 2%), abdominal pain (3%, 0%), nausea (4%, 1%)

Report side effects to the FDA at (800) FDA-1088 or Patients and caregivers may also report side effects to Genentech at (888) 835-2555.

For additional safety information, please see Tamiflu full prescribing information at